Ph.D. Dissertation:

Extraction, Identification and characterization of antioxidant and carbohydrate extracts of stem of okra plant and its use in the formulation of bread

Extraction using solvent (CSE), microwave (MAE) ultrasound (UAE) was used to recover phenolic materials from okra stems (as wastes in the agricultural industry). UAE showed the best performance in antioxidant activity and extraction efficiency. According to the phenolic diagram obtained by HPLC, catechin derivatives were the main phenolic compound as well as hydroxycinnamic acid derivatives and flavonols were other phenolic compounds in okra stem extracts. The emulsion produced with the carbohydrate extract of okra stems was relatively stable after 30 days of storage. Also, in this article, the functional characteristics of bread fortified with okra stems were investigated. The effect of wheat flour replacement with 4, 8, and 12% okra stem flour on dough rheology and bread quality was investigated. Dough rheology was performed using Farinograph and Broadner Extensograph and baking of bread by combining straight-dough and dough-sponge methods. There was a positive correlation between the percentage of replacement of wheat-stem okra flours and water absorption capacity. Dough consistency was positively correlated with the percentage of substitution of wheat-stem flour in okra. The addition of okra stems weakens the elasticity of the gluten structure and creates a bread core with less elasticity and a compact microstructure. The specific volume of bread changed significantly with the percentage of replacement and had a negative correlation with it. A significant decrease in the firmness of fortified bread kernels was observed with increasing the replacement percentage. The results showed that in bread preparation, wheat flour can be replaced with okra stem flour up to a maximum of 12% without negatively affecting the quality of bread.

Keywords: Fortified bread, okra stems, antioxidant activity